I already have the Gil Offshore front motor mount and wanted to know if anyone used the mid plate mount too?

They're primarily used in staggered setups.
My staggerd Scrab used the back plates on both motors though. If you want to use them, you'll need to have the bell housing machined to take in accout the thickness of the plate between the block and bell housing.
Gary

Would they be worthwhile in a side by side set up?

I dont think I've ever seen a failure of TRS or SSM tranny tailstock mounts. So it may be a bit of overkill for a plug in setup.

I've got them in my side by side setup.

Would there be any benefit to a TRS plug in style setup?

I had them in my boat too... along with the SSM rear mount.

Here is mine on a plug-in side by side set up.

Jim

Reed, what does the SSM rear mount look like?